The long term goal of the proposed project is to develop antiphonal calling as a model of the primate cortex for studies of the auditory system and human speech. Antiphonal calling is a natural (i.e., untrained) vocal behavior that involves an animal producing their species-specific long distance call in response to hearing the same call produced by an occluded conspecific. As this behavior involves perceiving an acoustic communication signal from a conspecific and generating a planned vocal response, it represents an analog to human speech and can be used to study mechanisms underlying this auditory-vocal interaction. In common marmosets, antiphonal calling involves bouts of reciprocal antiphonal calls that adhere to a species-specific temporal dynamic. Earlier work demonstrates that this behavior can be experimentally induced and manipulated in a captive setting and is readily amenable for neurobiological inquiry. Specific Aim 1 will employ a functional neuroanatomical technique known as behavior-driven immediate early gene (IEG) expression. This technique has been used successfully to determine whether particular areas of the brain play a significant role in a behavior or task. Here the IEG technique will be used to test whether the sensory and motor are mediated by different regions of the frontal cortex during antiphonal calling. Specific Aim 2 is to record electrophysiological activity of individual neurons in the frontal cortex during antiphonal calling. The locations of these recordings will be determined based on the results of Specific Aim 1. The goal is to record from both sensory and motor areas of frontal cortex during this behavior to examine how neurons in the frontal cortex contribute to sensory processing and production of communication signals. GENERAL SUMMARY - Despite the fact that numerous individuals are afflicted with aphasic deficits that result from ablations to cortical networks, there presently is no animal model that can be used to dissect the problem. Frontal cortex is known to play a significant functional role in both the sensory and motor components of human speech and, as such, any model system that targeted this area of the primate brain stands to make significant advances. Here we propose use a natural (i.e., untrained) primate vocal behavior known as antiphonal calling to examine the neural mechanisms in the frontal cortex that mediate both the sensory processing and vocal production of an acoustic communication signal. The proposed project will use a functional neuroanatomical technique and electrophysiological recordings to examine the sensory and motor components of this natural vocal behavior. [unreadable] [unreadable] [unreadable]